Abstract The Co-Optimization of Fuels and Engines (Co-Optima) initiative from the US Department of Energy aims to co-develop fuels and engines in an effort to maximize energy efficiency and the utilization of renewable fuels. Many of these renewable fuel options have fuel chemistries that are different from those of petroleum-derived fuels. Because practical market fuels need to meet specific fuel-property requirements, a chemistry-agnostic approach to assessing the potential benefits of candidate fuels was developed using the Central Fuel Property Hypothesis (CFPH). The CFPH states that fuel properties are predictive of the performance of the fuel, regardless of the fuel's chemical composition. In order to use this hypothesis to assess the potential of fuel candidates to increase efficiency in spark-ignition (SI) engines, the individual contributions towards efficiency potential in an optimized engine must be quantified in a way that allows the individual fuel properties to be traded off for one another. This review article begins by providing an overview of the historical linkages between fuel properties and engine efficiency, including the two dominant pathways currently being used by vehicle manufacturers to reduce fuel consumption. Then, a thermodynamic-based assessment to quantify how six individual fuel properties can affect efficiency in SI engines is performed: research octane number, octane sensitivity, latent heat of vaporization, laminar flame speed, particulate matter index, and catalyst light-off temperature. The relative effects of each of these fuel properties is combined into a unified merit function that is capable of assessing the fuel property-based efficiency potential of fuels with conventional and unconventional compositions.

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哪些燃料特性可以提高火花点火发动机的热效率？

摘要 美国能源部的燃料和发动机协同优化 (Co-Optima) 计划旨在共同开发燃料和发动机，以最大限度地提高能源效率和可再生燃料的利用。许多这些可再生燃料选择具有不同于石油衍生燃料的燃料化学。由于实际市场燃料需要满足特定的燃料特性要求，因此使用中央燃料特性假设 (CFPH) 开发了一种评估候选燃料潜在益处的化学不可知方法。CFPH 指出，无论燃料的化学成分如何，燃料特性都可以预测燃料的性能。为了使用这一假设来评估候选燃料在提高火花点火 (SI) 发动机效率方面的潜力，在优化发动机中，个体对效率潜力的贡献必须以一种允许个体燃料特性相互权衡的方式进行量化。这篇评论文章首先概述了燃料特性和发动机效率之间的历史联系，包括汽车制造商目前用于降低燃料消耗的两种主要途径。然后，进行基于热力学的评估，以量化六种单独的燃料特性如何影响 SI 发动机的效率：研究辛烷值、辛烷敏感性、汽化潜热、层流火焰速度、颗粒物指数和催化剂起燃温度。